Six Key Ways Petra Nova Has Shown That Carbon Capture Works

The Petra Nova project is a carbon capture retrofit to a 240 MW slipstream of the W.A. Parish coal power plant in Texas. The carbon capture facility recently made headlines because it went temporarily offline, which CATF discusses in a separate blog post. The project, which is the United States’ first large-scale carbon capture project on a coal plant, was supported in part by a technology demonstration grant from the U.S. Department of Energy (DOE). The operations report that Petra Nova recently submitted to the DOE was one of the grants’ conditions. The report evaluates the performance of the facility over the first three years.

Here are six key takeaways from the report you need to know:

1. Petra Nova captured over 92.4% of the CO2 that passed through the unit over three years. The target for the demonstration was 90%.
2. The capture unit was highly reliable during the monitoring period. The forced outage rate of the capture unit totaled 9.5%. Many of the forced outages in the capture unit were not associated with the main CO2 capture equipment such as the absorber tower or stripper. The solvent, which contributes significantly to operating expenses, also did not present any unique challenges. Instead, forced outages were often associated with the more mundane equipment such as compressors and heat exchangers, which future projects can avoid by applying the simple lessons learned. Another set of planned outages added 4.7% to the time the capture unit was offline. According to the report, other outages were unrelated to the capture unit. During the three-year demonstration, there were 60 days when the coal plant was shut down, 42 days when the West Ranch oil field did not accept CO2, and 21 days of shutdown caused by weather (primarily Hurricane Harvey). The plant had to shut down for 88 days when the natural gas-fired co-generation facility (cogen) that powers the capture equipment was unavailable. This problem may be a unique problem for Petra Nova. Typically, cogen plants are highly reliable. But as the report notes, the cogen plant at Petra Nova was purchased overseas on the secondary market, suggesting that this factor may have contributed to reliability issues.
3. West Ranch stored more than 99% of the CO2 that it received from Petra Nova meeting DOE goals. The oil field uses CO2 for enhanced oil recovery, while permanently storing it deep underground.
4. Petra Nova was built on time and within budget and met all start-up requirements. The testing completed over two weeks in 2016 met all emission limits and other performance guarantees.
5. Volatile Organic Compounds (VOC) emissions were low. The report notes the three-year average was 2.85 tonnes per year (TPY), well below the permitted limit of 24.53 TPY. VOC emissions can increase with carbon capture if the capture solvent leaves the absorber tower. These low VOC emissions suggest that carbon capture is less likely to be polluting at levels that trigger Clean Air Act New Source Review (NSR) provisions, making retrofits less complicated.
6. The DOE report provides other future project developers confidence to begin capturing CO2 from gas, coal, and industrial projects. The reliability of the capture unit improved in each year of the demonstration period. Initial problems are not uncommon at first-of-a-kind facilities, but successful ones improve with time. Petra Nova registered those performance improvements. Petra Nova demonstrates that carbon capture works on a commercial scale in the power sector, supplementing decades of successful commercial experience with large-scale carbon capture in multiple industrial sectors. To advance carbon capture to broader use, however, Congress must get serious about addressing climate change. That means providing better incentives for using carbon capture, financial support for storage sites and CO2 transportation networks, and more support for research, development and demonstration to lower technology costs.